1. Field of the Invention
The present invention relates to a headrest device comprising: a headrest ascending mechanism which ascendably supports a headrest at an upper end of a seat back; a pressure receiving plate which is provided at the seat back to face a back of an occupant and which moves to a rear side in a vehicle body by an inertia force upon a rear-end collision of a vehicle; and transmission means which connects the pressure receiving plate to the headrest ascending mechanism and which operates the headrest ascending mechanism to ascend the headrest when the pressure receiving plate moves to the rear side of the vehicle body.
2. Description of the Related Art
When a vehicle is struck from behind, not only the head of an occupant seated in a seat falls rearward, but also the position of the head tends to be higher than when normally seated because the occupant jumps up from the seat by impact. In order to eliminate the drawback, Japanese Patent Application Laid-open No. 11-268566 discloses a headrest device in which the movement of a pressure receiving plate that moves rearward by being pressed by the back of the occupant upon a rear-end collision is transmitted via transmission means to the headrest; and the headrest is moved forward to near the head of the occupant; and the headrest is simultaneously ascended or raised.
However, in the above-described conventional headrest device, the headrest is raised by converting the rearward movement of the pressure receiving plate into the upward movement of the rod-shaped transmission means. Therefore, a compression load is applied to the transmission means when the headrest ascends. Accordingly, unless a thick transmission means with high rigidity is used, there arises a possibility that the transmission means is bent and buckled when the headrest ascends, which not only makes it difficult to raise the headrest with favorable responsiveness but also makes it difficult to secure a space for placing the transmission means inside the seat back.